Interpolating system



N0V.17,1931.k WA, KNOOP- 1,832,308

INTERPOLATING SYSTEM Filed Dec. 31.1928' s sheets-sneu 1 ATTURNEV N ov` 17. 1931. w- A, KNOOP 1,832,308

INTERPOLATING SYSTEM FiledlDec. 31, 1928I 3 Sheets-Sheet 2 V Mw n. b E .H P n w M Q w, Q. w. Q, w, n Q. w. r l W A H Q NN m9@ l V i S E ma E E n NN Y B Ll WN w am w D w JH EN imm W HW- S L Q UwmW- Wjw 1 h S Perl- ...LNH X s W MN. m Q. f4* MN n n N N nu mm @4m/H @M H@ @MQ/mw @HSM t GHGH. mmwpmxm *MT n .wf N NH i du... jznwjmmjzl Q 1 23g f j L l? 7 um, .N N\ S Nov.- 17, 1931. w. A. KNooP 1,832,308

I INTERPOLATING SYSTEM Filed Dec` 3l. 1928 3 Sheets-Sheetl 3- Patented I Nov. 17 1931 UNITED STATES PATENT oFFlcE WILLIAM A. KNOOI, OF HEMPSTEAD, NEW YORK, ASSIGNOR TO BELL TELEPHONE LABORATORIES, INCORPORATED, OF NEW YORK, N. Y., A. CORPORATION OF NEW 'YORK INTERPOLATING SYSTEM l Application led December 3,1, 1,928.- Serial No. 329,439.`

This invention relates to synchronous telegraph systems, and particularly to interpolatingreceiving systems for use with high speed telegraph conductors such as loaded subma-A rine cables.

Objects of the invention are to simplify and to increase the eilectiveness of interpolating receiving systems.

' Another -ob]ectis` to repeat signal impulses from a plurality of lo'w speed lines into a single high speed line, and,'after transmission thereover to interpolate the single impulses which have been lost during transmission and retransmit all impulses into a plurality of lines corresponding tothose at the originating end.

In high speed signaling transmission systems short signal impulses are attenuated because, of the characteristics of the transmission line, and must be rebuilt at thereceiving end or the relaying point. Heretofore. receiving systems for this purpose have beeny commonly termed vibrating relay systems. This expresion is somewhat misdescriptlve of the system of this invention because short impulses are rebuilt without necesarily vibratingany relays and therefore in this speciication the expression interpolating receiving system will be used to del-lne a system which restores or interpolates short signal impulses which have been attenuated to such an extent -that they are incapable of controlling a receiving relay or arelay for retransmitting -.the impulses into the next line section. It has been 1the practice heretofore to interpolate at the receiving end of a telegraph circuit missing signal limpulses of unit length which has been practically completely attenuated during transmission because of their high frequency. The applicants copending application, Serial No. 253,239,^filed February lO, 1928, 'disclosed aninterpolat-ing systhe' relay armatures againstcontacts of^op posite polarity whereby unit impulses of alternate positive and negative polarity are generated as the'brushes on a rotary distribceived the current in the line windings increases, thereby'moving the relay armatures agalnst contacts of like polarity to generate a series of impulses ofthe polarity corresponding to the receivedimpulse of greater than unit length.

The system of the present invention differs from th`ose previously known, notably that disclosed in applicants copending application, in that the separate interpolating and line windings have been eliminated, the line volt-age and the interpolated voltage being superim osed on the same windings of each relay. urthermore, a system is disclosed in which a plurality of interpolating receiving relays receive signals from a plurality of channels on a high speed telegraph conductor or cable and retransmit them directly into a plurality of low speed lines.

In the drawings, Figsfl and 2 show a schematic circuit in which any odd number of receiving relays may be used, three being shown for the purpose of illustration;

Fig. 3 is a modilcation of Fig. 2, wherein vacuum 'tube storing and impulse lengthening arrangements are used 1n conJunctlon with an odd number of relays;

Fig. 4 shows curves representing the operation of the circuit arrangements shown in Figs.' 2 and 3. Y

- Description of the circuit of Figs. 1 and 2,-Arranging Fig. 2 at the right of Fig. 1, a system isshown wherein nine transmitters, A, B, C, D, etc, at station X are respectlvely connected in rotation by cable 10 to a corresponding number of printers designatfed A', B', C', D, etc. at'station Y. The

cableis designed for high speed transmission and in order that low speed lines may be connected thereto at the sending end, the transmitters vin Fig. 1 may be replaced by a plurality of relays (not shown) operably connectedto -low speed lines. This may be accomplished in one way, which isfnot shown in the drawings, by having the low speed lines each terminate in a rotary distributor, the receiving segments of which may be connected to a. receiving relay. Each. re-l ceiving relay would reproduce the signals be longer-than those ofthe sending distributor, for instance, should there be three receiving distributors the receiving segments would be approximately three times the Vlength of the sending segments, the brushes of the receiving distributors would with respect to each other be offset in a progressive order the distance of one sending segment so that the receiving relays would be successively operated and released in the order of the relative brush positions, and the brush kat ofthe sending distributor would be aligned 'with the receiving brush in last position.

In this way one receiving relay would replace each transmitter.

In order torepeat the high speed signals incoming at station Y over a plurality of low speed lines or, ifstatioii is the termi:- natlng point, to slow-acting selector magnets in the printers, the signals from each transmitter are interspersed on, the cable with those from the -other transmitters. This is because slow-acting repeating relays or the selector magnets will not respondato the impulses as received from the cable but il will respond when these impulses are lengthened in the course of reproducing them to the repeating relays or print'ers by `the receiving relays. As the operation of 'interspersing the transmitted impulses de- L pends upon the reception of the impulses fromI the d iiierent transmitters successively the transmitters are connected in groups .to the sending distributor 11 at station X, the

; transmitters in each group corresponding in vlcessively and this operation is repeated un-l number to the receiving relays at station Y. -The transmitters ofeach groupv are so connected to the distributor 11 that one impulse from each transmitter in a group is sent suctil all five impulses ofl each transmitter in the group aresent. AIn other Words, an impulse from transmitter A is' followed by an impulse from transmitter B` and then by an impulse from transmitter C, this operation being repeated with the other impulsesfrom each of the transmitters A, B and C, until all five impulses from each of the transmitters are sent. Transmitters l),l E, F, in a group, and G, H, I, in another groupl are manner'l as that described above for the group of transmitters A, B and C.

The impulses from transmitters A, B and C are received at station Y, by receiving distributor 12 as'shown in Fig. 2 and successive impulses impressed in succession on three receiving relays 13,' 14 and 15, respectively. Similarly,'the impulses of each of the three transmitters of, the other two groups are also impressed on these relays.

are of the polarized type and each is biased 'momentarily through distributor-'12 by and in the opposite direction lto the relay pre1 ceding it'.

live and dead segments for each transmitter v The armatures ofrelays 13, 14 and 15 are so that for the nine transmitters, with the received signals split three ways as shown,

each segmented printer ring has thirty alternate live and dead segments. lThe printer rings are concentrically arranged with the receiving ring set 12. one brush arm being provided with brushes for the four ring sets disposed in radialv alignment. The live segments of the printer ring sets are approximately twice the length of-the dead segments so as to permit the .use of slow-.acting printer magnets, or repeating devices should further transmission be desired. In practice'these live and dead segments are made of equal lengths in order that a slight mal-adjustment of the brushes may be permitted without causing error. The live segments A A2, A, ALand A', are respecare connected to the magnets of printer B',

and so on for the remaining live segments,

each roup of live being connected to the magnets of a printer as shown. In order to have `the. proper sequence of operation for the printers the segments of each of the three printer ring sets 16, 17 4 and 18 are so posi'f tioned with respect tothe live segments of re.- v

' ceiving ring set 12 that when' a receiving brush 19 on ring set 12 is passing through the center of a receiving or live segment'the brush of the printer ring set containing'the corresponding live segment, is in the center of the dead segment immediately at the left hand side of such corresponding pliversegment. In other words, should brush 19 be passing the center of segment A3 of ring set 12, brush 20 would be in the center of the dead segment to theleft of segment A's. Therefore, in accordance with the arrangement of the live segments of ring set 12 and the corresponding segments in ring sets 16, 17 and 18, printers A', B, C', D', etc. will be operated in sequence.

In order to interpolate impulses at station Y to replace thoseof unit length which are lost or greatly attenuated during transmission, currents of alternate positive and negative polarities are generated from a local source of potential 26 as brushes 19, 20,521 and 22 rotate over their respective ring s'ets, providing, of course, that no signal impulses of two or more units length are receivedV in the interim from the cable. The relays 1314 and 15 respond in rotation as brush 19 rotates over the live segments of ring set 12, and therebyassume alternately opposite positions which relationship is maintained regardless of what odd number of relays aie employed. During the rotation of the brush 19, Vt-he relays 13 continue to vibrate'to preserve the relationship. This relationship causes to be trans! mitted from battery 26, as brushes 20, 21 and 22 rotate over the printer ring sets 16, 17 and 18 respectively, longimpulses of alternately opposite polarities to the printers A', B and C', an .impulse to printer A' being followed by an impulse to printer B and then by an impulse to printer C.'4 These impulses to vprinters A', B andC are continued, should no long impulses be received from the cable, until all five impulses are received bv each printer, at which time the impulses will then be directed to the prin-*ers D', E', and F', and so on. In the event that a long impulse is received from the cable, the cable current will be superimposed on the biasing current inl any one or all of the relays 18, 14 and 15 and will be of sufiicieiit strength tobperate the relay,

or hold it operated should the armature thereof bein the desired position regardless of the biasing current. The biasing current is ad- ]usted to a suitably small valve as compared with the cable current of a long impulse.

The practice of reversing polarity between certain channels o r within channels, in order to produce a more perfect balance of polarities on a submarine cable on a multiplex signaling system, has not been shown. It may be accomplished by reversing. the 'battery leads of the transmitters shown in Fig. 1, at any point between or within the transmitters and valso by connecting each'of the battery leads of the three printer sets, shown Jin Fig.

nate positive and negative polarity transmitted from the distant station X are greatly attenuated during transmission and consequently do not operate receiving relays 13,`

14 and 15, butwlien the signals made up of impulses of two orniore units length of like polarity, are received, the current thereof rises to an amplitude suiiicient to operate or hold operated the relays arranged to receive the second and subsequent unit parts of the signal.' v Itwill be noted that relays 13, 14

\ the operation of one relay depends upon the position of the one preceding it when no sig- 'nal impulses of value sufiicient relays are being received.

As an illustration, let is be assumed that there are no eilective impulses being'received to hold the "from the cable and relay 13 isin the position shownat the time brush 19 is passing over V segment A, of ring set 12. When brush 20 reaches segment- A'1 the `circuit extending from the positive pole of battery26 over the right hand or positive contact and armature of relay 13 through the first magnet of printer A1, to the negative pole of battery. 27 is coinpleted and the magnet of printer A'l operates.

Whenbrusli 19 reaches segment Brtlie circuit is closed extending from the positive pole of battery 26 through the right hand contact of relay 14segnient B1, brush19, resistance 30 to,.ground. -A current flows-from batter 26 through the windings of relay 14, and this current is of suliicient strength and in such and armature of relay 13, and the windings direction as to operate relay V14toitsV left hand or negative contact. When brush' 21 reaches segment B'1 the operation of relay 14 to its negative contact closes a circuit extending from the negative pole of battery 26, left hand contact and armatui'e of relay 14.

through the winding of the first magnet of printer B to the negative pole of battery 28.'

No current 'lows-in'this circuit, and therefore the first magnet of printer B' does not oper- A ate. 'W'lien brush reaches segment C1',

current .fows 'from negative pole of battery '26 through the windings of relay 1.5 over segisp nient Cl and brush 19 to ground at resistance completes the circuit extending` through the winding of the first magnet of printer C to the negative pole of battery 29. The batteriesin this circuit aid each other yand the magnettherefore operates.

When brush 19 reaches segment A2 the circuit is closed from ground at resistance 30,

. brush .19 and segment A2, through the Windings of relay 13, right hand contact ofrelay 15 to the positive pole of battery 26. The

A current in this circuit flows through relay 13 tinue to reverse their positions so that impulses of alternate positive and negative polarities will be generated when no long impulses are received from the cable, the magnets of printers A1, B1, C1, etc. responding when, and only when, impulses of positive polarity are, generated.

Referringto Fig. 4, a clear understanding of the method of interpolating impulses of unit length in a message whereof the transmitted unit impulses have been lost in transmission, may be had. Let curve a represent the signal wave as it is transmitted from station X, curve Z) the 'same wave as it is received at station Y with theimpulses of unit length greatly attenuated and curve c indicates the operation of the receiving relays. In curve c the full vertical lines indicate the polarities of the signals regenerated at station Y, in response to either the impulses received from the line or the interpolated impulses, to opcrate the relays and the dotted vertical lines indicate the polarity of the interpolated impulses which tend to operate the relays at the time the relays are under the control of incoming line signals. In curve a the rst impulse is of unit"length and of positive polarity but by the time it passes from station X to lstation Y it is greatly attenuatedas shown in curve Z).V This impulse flows through the windings of relay 13 when brush 19 passes over segment A'l, but it is ineffective to operate the relay. As hereinbefore assumed, the armature of relay 13-is in engagement with its right hand or positive contact, indicated' by the first vertical. line in'curve c, and when 'brush 20 reaches segment A1l the first magnet ,of printer A1 operates. As brush' 19 passes on to segment B1 an operat- 1 current flows from battery 26 through wmdings of relay 14 to 'ground through resistance 30. This current is in such -a direction as to tend to operate relay 14 to its negative position as shown, and inasmuch as the incoming signal impulse simultaneously received by segment' B1 is of unit length and consequently' low in amplitude the' current Yfrom .battery 426 predominates and operates the relay tou its negative position, as shown by the second full vertical line 1n cuuve c..

When brush 21 reaches segment B1 of ring set 17 negative battery 26 is connected to negative battery 28 through the first magnet of printer B1, but` the magnet does not operate because of opposing polarities.

When brush 19 reaches segment C1y the current from battery 26 Hows through the windings of relay 15 in such a direction as to tend to operate the relay to its positive position, as shown by the third full vertical line of curve c. Inasmuch as the third impulse designated in curve b as positive is of unit length the current from battery 26 not only tends to operate but does operate relay 15 to its positive contact., As the brushes continue to rotate, brush 22 reaches segment C1 of ring set 18 and connects positive battery 26 over the right hand Contact of relav 15 andthrough the first magnets of printer C', 'to negative battery 29, thereby sett-ing the n1agnetin operated position. When brush 19 reaches segment A2 the circuit extending fronrgxrounm resistance 80, brush 19, seg- 'menti contact and armature of relay 15 to positive battery 26, is closed and the current through' relay13 is insuch a direction as to operate the relay to its negative position as indicated by the fourth vertical line in curve 0. As b1f.ush 20 rea-ches segment A-2 the negative pole of battery 26 isconnected through' the Winding of the second magnet of printer A' 2, winding of relay 13,l right hand to the negative pole of battery 27, but `due to 'opposing poles being interconnected the magnet does not operates This operation is repeated as long as no effective signal impulses of two or more units length are received and the interpolating impulses are therefore of alternate positive and negative polarities.

However, it will be noted that the fourth impulse in curve b is the beginning of a long impulse of three units length and consequent-` ly the line current of the long impulse rises to an amplitude suicient to predominate over the current from battery 26 in controlling the receiving relays connected to the segments over which brush 19 is passing at the time. Accordingly, as brush 19 reaches segment B2. the second unit of the long negative .-strengthof @this impulse'is sufcient to hold relay 14 in its negative position, although at the time the interplatingcurrent from battery 26 was flowing in the opposite direction through the windingsf-fof relay 14, so as to tend to operate'the relayto its positive rposition." The polarities ofthese opposing currents vare indicated vin curge 'c by the fifth vvertical line, the sol id portion representing that of the'lne curt,and the vdotted portion representingthat of the interpolating current. When brush 21reaches segment B2 the negative poles of battery 26 and 28 are interconnected through the Nwinding of 11" slgnal 1s belng received from the line and the o tssaec the second magnet of printer -B and the magnet remains normal.

When brush 19 reaches segment C2 the current from battery 26 ows through the windings of relay 15 in such direction as to ordinarily cause the relay to remain in its positive position but inasmuch as the strong negative current on the line is flowing at the same time in the opposite direction through the relay windings the relay armature moves over to its negative contact. In curve c the polarities of the currents fiowing through the windings of relay 15 are represented by the sixth vertical line, the dotted portion representing the tendency of the interpolating current and the solid line representing the effective line current voltage. vAs brush 22 reaches segment C2 the negative pole of battery 26 is connected to the negative pole of battery 29 and therefore the second magnet of printer C' does not operate.

At the end of the long impulse of three units length the line current reverses to form a long signal of positive polarity and as brush 19 reachessegment A13y the interpolating current from battery. 26 becomes eflective to move relay 13 to its positive contact because the line current has dropped oi to zero value.. The seventh vertical line in curve c represents the positive polarity ofa' regenerated or in-= terpolating current, overcoming the 'line current voltage which has now reached a negligible value. The remaining portions of curves b and c will be readily understood from the foregoing.

Description of circuit of Figure 3.--Fig -3 g shows a modification ofthe'receiving equipment shown in Fig. 2, wherein a pair of vacnum tubes are employed with eachreceiving relayfor storing thesignal impulses and for upsetting the normal balance of space current values in any one pair of vacuum tubes to control the operation of its associated relay. In this figure the grouping of transmitters and printers is the same as that shown in Figs. 1y and 2, the only difference in'the equipment being, in additionto the vacuum tubes, the provision of a printer relay for each group of printers and the differential character of the receiving relays. As in Fig.

2, there is an odd'number of receiving relays,

such as those `designated 41, 42 and 4 3 and these. also are assumed to be' int alternately positive andnegative positions `so that when there are no signals being received at station' Y the impulses which are interpolated' will be of alternate positive andnegative polarity.

When the first part of a signal of two or more units. length, say, of positive polarity, is received `over segment A1 :of the receiving ring set 44, a voltage dropis produced across resistance 45. This voltagedrop.` is appliedv Athrong condenser 46 to'the si al common ring 4 l brush 48 and segment 1 to the condenser 49 and grid of vacuum tube 50. Bat? rent in tube 50 and the left hand Winding of relay 4l 'ifs increased. The'second vacuum tube 53 of the first pairhas its grid normally biased negatively with respect to its filament by a battery 54 and as'the space current of v tube 50 flows through a resistance 52 a voltage drop is produced across the resistance in such a direction that a positive potential is impressed on condenser 55 to make the grid of tube 53 more negative, thereby causing a decrease in the space current in tube 53 and the right hand Winding of relay 4l. The predominance of current in the left hand Winding of relay 41 holds the armature of the rei lay against its right hand or -positive contact.

The interengagement of the armature and right hand contact of relay 4l allows a positive current to flow from battery 56 through the windings of printer relay 57 and resistance 58 to ground. Relay 57 moves its armature to its right hand'- or positive contact andv as brush.y 59 'reaches segment Al of printer ring set 60 a positive current fiows from battery 56, right hand contact of relay 57, brush 59, segment. Althrough the winding of the first magnet of printer A1 to the negative pole of battery 61, thereby causing the magnet to operate.

The positive current iiowing through relay 57 produces-a voltage drop across resistance 58 in such a direction as to .make the filament of tube 62 of the second pair of vacuum tubes more positive with respect to the grid and should no signal be received when brush 48 reaches segment BLthe effect of the voltage drop across resistance 58'would cause a de crease in the space current in tube 6.2 and the left hand 'winding of relay 42. Included in roo the plate-circuit of tube 62 is resistance 63 and the "voltage drop across this resistance would impress a negative charge on condenser 64 and this in turn would make the :grid vof tube 65l of the second pair positive with respect to its associated filament. Consequently, the

space current in tube 65 and the right hand winding of relay 42 is increased. This would result in relay 42 holding its armature at its left hand .or negative contact as shown. But

i as 'it was assumed above that the incoming signal was of two or more units length the voltage drop across resistance 58 is overcome by the signal voltage because the second unit of the positive signal is being simultaneously received over segments B1 and the resulting action of the tubes 62 and 65'is the same as` that described above for tubes 5o and 53. Therefore, the action of tubes 62 and 65 in response to the second part of the long positive signal causes relay 42 and printer relay 66 to move their respective armatures to their right hand or positive contacts. When brush 67 reaches segment B of ring set 68 a positive current flows from battery 56 through the A. winding of the firstpmagnet of yprinter B to the negative pole of battery 69 and the corresponding segment C1.

magnet operates.

In the 'circuit extending through 4the windings of relay 66 there is included a resistance 70 across which a voltage drop is produced when the positive current from battery 56 operates printer relay 66. This voltage drop is applied to the filament of tube 71 of the third pair of tubes and is in such a direction as to make the filament more positive with respect to its associated grid when brush 48 tive charge on condenser 73. This charge makes the grid of tube 74 of the third pair more positive with respect to the lilament and' the space current iiowing through the E right hand winding of relay 43 is therefore negative' `pole of batte tends through the win ing of the first magincreased. rI`his unbalance of the space currents in relay 43 causes the relay armature to engage its left hand or negative contact to close the Vcircuit extending through the windings of printer relay 75,'resistance 76 to ground. vRelay 75 operates and connects the negative pole of battery 56 when brush 77 reaches segment C1 of ring] set 78, to the .net of printer C but this magnet does not operate at this time because batteries 56 and 79 are opposing. The voltage drop produced across resistance 7'6 applies negative potential 'to the filament of tube 50 and if the next transmitted impulse is of positive polarity and of unit length no effective si al nmi will be received from the cable. There ore the negative potential set up on the lament oftube 50 by the resistance .76 causes the space current in ltube 50 to be increased and the corresponding current in tube 53 to be' decreased thereby operating relays4 41 and 57 to their positive positions. The positive pole of battery A56 is therefore connected through the second magnet of printer A to the negative pole of battery 61 when 'brush 59 reaches segment Az, and the second magnet of printer A is operated. P

79. The circuit exrelay, and means stronger of ,the two This operationis repeated until the printe ers A B and C have been res ectively set .inthe positions corresponding to the three characters transmitted by transmitters A, B and C shown in Fig. 1. Any number of groups of printers such as D', L and F',

.and Gr', H. and I may be added and these operated in sequence by relays 57, 66 and 75. It will be note'd that when no effective signals are being received that the regenerating resistances 58, 70 and 76 produce a biasing voltage for the tube following and thereby cause unit impulses of alternate positive and negative polarity to bepproduced. In this way the impulses of unit length which are lost in transmission are inserted at their proper positions byemploying pairs of vacuum l tubes to control the operation of a receiving relay, the number of pairs being determined by the number of printers desired.

Operation of the circuit of F gu-re 3.--

The operation of this circuit shown in Fia'. 3v

is substantially the same as that described rbove for Fig. 2 taken in conjunction with ig. 4.

In addition to embodiments of the invention comprising odd numbers of receiving relays there arevmodiications includin even numbers of receivin relays. Some o these are disclosed and c aimed specifically in a subsidiary patent application Serial No. 432,288, iledcMarch l, 1930.

What is claimed is:

1. A s nchronous interpolating system, characterized in this that it comprises a luralityof relays, means whereby lsaid re a s are successively connected in rotation to capable of ybein affected by the received 'impulses and to e capable of being simultaneously aected by the precedin relay and in the opposite sense to the impu se operaty ing the preceding rela the impulses simultaneously aiiecting eac relay being effective upon common relay windings.

2. A -synchronous interpolating system having a transmission line, characterized in this that it comprises a plurality of relays,

means whereby said relays are successively connected to said line in rotation to be ca- ,plable of being aiected by the signals received om said line andto be capable of being simultaneously affected by the preceding relay and in the opposite sense to-the signal operating the precedinur rela each of said nela s being provide wit windings upon w ich the signals from saidline are su er` imposed,I on the sinals from the prece ing or 'registering the operation of said relays in response to either the signals received` from said line or to the. sig- `nalsreceived fromthe preceding relay, said relays being operated in `response to the signals simultaneously received.

3. A synchronous interpolating system :,ssasos havin a transmission line, characterized in this, t at it'comprises a plurality of receiving relays, means wherebysaid relays are successively connected to said line, to be capable of being affected over common windings by the impulses received from said line and by the impulses simultaneously received from the preceding relay, and inthe opposite sense to the impulse operating the preceding relay, and a plurality of relays respectively associated with said receiving relays and ar- Iranged to be operated by said receiving relays to produce -a record consisting of the impulses received rom said line and the impulses received from the preceding relay, said relays being operated in response tothe stronger of the two signals simultaneously received.

.4. In a synchronous telegraph system, an

interpolating receiving circuit, characterizedA in this, that it comprises a plurality of relays respectively connected to a plurality of printer rings on a receiving distributor and each having windings for receivin incoming signal impulses, and a plurality o means respectively associated with said relays for impressing on each of said windings impulses received from the preceding relay to generate unit impulses of alternate positive and negative.. polarity when the incoming signal impulses a-re ineiective to control and operate said'relays.

5. In a synchronous telegraph system comprising a line, a receiving distributor connected to said line and an interpolating circuit, characterized in this, that a plurality of relays having windings for receiving incoming signal impulses, respectively connect a pluralityof printer rings to a receiving ring on said distributor and a plurality of elements respectively associated with said relays-for cooperating with a plurality of segments on said receiving rings to regenerate alternate positive and negative impulses and means for impressing on each of said windings concurrently with the signal impulses the regenerated alternate positive and negative impulses for interpolating said impulses in their proper places betweenthe impulses received from said line whenever said relays fail to respond to the line impulses.-V

6. In a synchronoustelegraph system coinprising a line, a rotary distributor connected to said line and an interpolating circuit,

garacterized in thi-s, that`a plurality of reys having windings for receiving incoming` signal impulses, a corresponding number of ,circuits each including vthe armature and contacts of one of said relays, the. windings -of another of said relays and a resistance elenient for transmittingl over said windings unit impulses of alternate positiveand negative polarity, anda plurality of groupsv of receiving segments on said distributor for transmitting impulses from said linel over Aadapted to supply positive and negative im-` pulses, synchronous switching-means for distributing received signal impulses to said l. repeating devices in rotation and for concurrently superimposing on the windings of each repeatingdevice a current impulse from. the preceding device of such polarity as to tend to operate said device to a position opposite that-ofthe preceding device, 'and means for utilizing impulses lfrom thefir'st mentioned devices. i

9. Ina synchronous multiplex telegrap system, a sending station and a receiving sta- "tion, a. transmission circuit interconnecting said stations, a .plurality ottransmitters at the sending station, means for applying signal impulses from said pluralitv of transmitters to said circuit in rotation, the impulses of one transmitter interleaved with those of` the other transmitters, a plurality of receiving relays at the receiving station, and means at said receiving station for applying im,- pulses to said receiving relays in rotation, whereby all impulses from any one transmitter may 'be received on one only of said relays, and means comprising said relays for interpolating at the receiving station signal impulses of alternate positive and negative polarity to replace those which have been 'appreciably attenuated during transmission.

10. In a synchronous telegraph receiving system,.a local-source of potential, a pluralityof relays eafch'having a double winding v and a movable armatureoperable between two contacts vconnected to opposite poles of i distributing received signal impulses to the double winding of. each relay in rotation, a plurality of circuits each including one of said armatures and a resistance element, each of said circuits being effective to superimpose an impulse fromithe armature of the preceding relay concurrently with a received signalimp'ulse, onboth windings of each of said relays, the former impulses being of such polarity as-to tend to operate the armature of s uch relay to a position. opposite that of the armature of the preceding relay, signal resaid source, synchronous switching means for cording means, and other synchronous switching means, for connecting the armatures of the relays to saidv recording meansin rotation.` 1

y 11. In asynchronous telegraph system,

i comprising a pluralitycf transmitters ar- 'a plurality of printer rings on said distrib- `ranged in groups, a line connected to said utor corresponding in number,I to.A the transmitters in a group, a plurality of circuits each v comprising a localsource of current, the arpulse transmitters for said line, a transmitl mitters.

transmission line,

mature and contacts of one relay and the windings of the next succeeding relay capable of operating said relays in rotation to alternate positive and negative positions when said relays fail to respond to the received impulses, characterized in this that the received impulses and impulses from said local source are simultaneously applied to common windings on said relays.

12. A synchronous telegraph system com-v prising a transmission line, a plurality oi:l imting distributor, and a receiving distributor, at the receiving-end of said line having a plurality of receiving rings respectively arranged to receive impulses from said trans- 13. A synchronous telegraph system coinprising a relatively high speed transmission line, a plurality of low speed transmitting devices arranged in groups, meansjfor interleaving the impulses of one transmitting device with those of theother transmitting devices in the same group for transmission over said line, a relay for receiving from said line the impulses of each transmitting device', a

source of potential at the receiving terminal of said line arranged to be impressed on each of said relays concurrently with said line inipulses through common windings on said relays and capable of producing impulses of alternate positiveand negative polaritygwhen the line impulses are ineffective to operate the relays, means for interpolating said impulses of alternate positive and negative polarities in the received signals to replace impulses lost during transmission over said line, and slow acting devices for combining and registering the received` and interpolated impulses of each transmitting device separately. "i 14. In a synchronous telegraph system, a a plurality of transmitters arranged in groups, means foriiiterleaving the impulses of one transmitter with those of the other transmitters in the same group for transmission over said line, a plurality of pairs of three electrode vacuum tubes, each I pair arranged to receive all the impulses from one of the transmitters in a roup, differential relays each having its win ings respectively connected in the plate circuits of one pair of vacuum tubes, said relays being responsive to a train of received impulses vof one polarity, a movable armature and a pair of contacts on each of said relays, a sourceof potential having its oppositel poles respectively connected to said contacts, printer relays having windings respectively connected to each of said armatures, and means associated with each of said printer relays for operating the next succeeeding differential relay, when transmitted impulses are of alternate positive and negative polarities.`

115. In a signaling system, aline, a plurality of three-electrode vacuum tubes associated with said line, means for applying signal voltages to the grids of said tubes in rotation, a plurality .of relays connected to said tulies, a4 local source of potential, and means for applying to each of said grids in rotation a jvoltage from said loc'al source simultaneously with a signal voltage from said line, the volt# 'age from the local source being eii'ective to operate the relay only when no signal current of operating value is present in the relay winding.

16. In a signaling system, a plurality of pairs ot' three electrode vacuum tubes, means for applying signal voltages to the grids of the first tube ofb'each pair in rotation, a pluralityof diii'erential relays each having windings respectively connected in the output circuits of each pair of tubes, a local sourceof potential, means for applying lto'each grid of said pairsof vacuum tubes a voltage from said local source simultaneously with a signal voltage', the voltage from the local source being eilective-v to operate the relay only when no signallvoltage of operating value is present.

pairs of three electrode vacuum tubes, means for applying signal voltages to the grid of the rst tube of each pair in rotation,a plurality of differential relays each having windings ren a signaling system, a plurality .of i

spectively connected to the output circuits of eachy pair of said tubes, and normally arranged in balanced circuits, a local source ofA potential, means for simultaneously applying to each ofthe windings of one of said relays4 a yolta-ge from said'local source with a signal voltage, local source being ei'ectiveto operate the reconcurrently the voltagel from the lay only when no signal voltage `is present, A

and coupling, means between the output of 1 one tube andthe input of the other tube of each pairf for varying the space current of said. other tube in the opposite sense to the space current of the-first tube,'whereby lthe effective operating current of the associated relay is increased.

18. In a synchronous telegraph system, a'

i the impulses a plurality of transmitters arranged in groups, means for interleaving of one transmitter with those of the other transmitters of the same group for transmission over said line, a plurality of pairs of three electrode vacuum tubes each transmission line,

' pair arranged to receive all the impulses from pulses, and a .condenser one transmitter in each group,diferential relays each having its windings respectively connected in the plate circuits of one oi'said pairs of vacuum tubes, said relays being responsive to a train of received impulses'of one polarity, a movablearmature and a pair of contacts on each relay,-a source of potential having its opposite poles respectively connected to said contacts, printer relays each having awinding connected to one of said armatures, and impedance element associated with each of said printer relays for causing the operation of. the next succee diierential relay when the received impulses `are of alternate positive and negative polaril ties. Y

19. In a synchronous telegraph receiving system, a local source ofpotential, a plurality or' relays each having;l a movable arinature operable,between the contacts connected to opposite poles of-said source, and having differentially operated windings, a pair of three electrode vacuum tubes associated with each relay, a plurality of sources of plate potential respectively connected to said relays through the windings, synchronous means for -elect a change in voltages between the grid and filament of the first tube of each pair in rotation to vary the 1 normal space current of said first tube, and condensers respectively connected between the tubes of said pa'rs for utilizing the changes in space currents of the first tube to the opposite sense in the' space current of the second tubes, said changes being utilized to increase the elective operating current in the relay, 'the changes due to the regenerating voltages being effective to operate the relays only when no signal impulses are received.

In -witness whereof, I hereunto subscribe my name this 28th day of December, 1928.

WILLIAM A. KNOOP.

distributing received signal to the grid of one tube of each pair to increase. or decrease the space current therein in accordance with the polarity of the received -Limindividual to each pair of vacuum tubes arranged between the plate circuit of one of said tubes and the grid circuit of the other of saidtubes, wherey a change in space current in one tube is utilized to cause a change .in the opposite sense to the space currentin the other of said tubes,lsaid changes in in opera the armature o f the associated relay to either of its associated contacts to repeat the signal.

20. In a 'synchronous' telegraph receivingv system a local source of potential, a plurality of receiving relays eac armature operable between two contacts connected to opposite oles of said localsource and having two d erentially operated windings, a pair of three-electrode vacuumtubes space current aiding y l having a movable associated with each relay, and connected ico los

ns l 

